SPECIAL FEATURE: TRANSBOUNDARY
ANIMAL DISEASE CHANGES IN EASTERN AFRICA
Over the past few years, the livestock health situation in eastern
Africa has varied considerably, being to some extent dictated by weather
variability and associated nomad/livestock movements.
Drought and Rinderpest
Until about four years ago, it was considered that rinderpest was confined
to southern Sudan and the contiguous pastoral areas of Uganda, Kenya
and Ethiopia (the Southern Sudan axis), plus the Afar region of north-east
Ethiopia. There was, until then, movement of livestock from the southern
Sudan axis to peri-urban slaughter houses near Nairobi, and it was considered
that this source of infection posed the greatest danger for the rest
of Kenya and the countries to the south.
Between 1992 and 1997, there were periods of drought in parts of Somalia,
eastern Kenya and northern Tanzania, the most serious occurring in 1996/97.
At the end of 1994/95, rinderpest was detected in game in Tsavo National
Park, Kenya, and investigations indicated that the culprit virus had
originated from the Kenya-Somalia border area. The problem with this
particular strain was that it was a "low-profile" virus that
caused mild disease in cattle, making detection very difficult. In October
1996, the virus was detected in game in Nairobi National Park, and by
December it was found in cattle on the Tanzanian border.
The drought at the time, as usually happens, brought about increased
movements of Maasai herders between Kenya and Tanzania, in search of
grazing for their cattle. There was also greater interaction between
cattle and game. For example, because of prevailing drought conditions,
the Kenya Wildlife Services was compelled to permit cattle grazing in
parts of the Nairobi National Park. It was the combination of these
factors that both precipitated and facilitated the spread of rinderpest
into northern Tanzania in January 1997. High levels of drought-associated
mortality helped mask the presence of rinderpest.
Various projects were initiated in response to the emergency, and collaboration
between FAO/EMPRES, OAU, EU and the Governments of Kenya and Tanzania
was very close. It was decided that although funding for the projects
was awarded on a compartmentalised country-by-country basis, the operation
would be transboundary, and all work would be very closely integrated.
It would be focused on rinderpest and would be time-bound.
Mass vaccination combined with intense publicity, surveillance, sero-monitoring
and improved laboratory diagnosis was undertaken in a co-ordinated manner,
drawing considerable resources from the Kenyan and Tanzanian Governments,
PARC, EU, UNDP and FAO. Another notable feature of this work was the
enlisting of wildlife specialists to assist with the investigation of
rinderpest in wildlife (kudu, eland and buffalo), which were more severely
affected than cattle. Joint meetings of veterinary and wildlife experts
from both Kenya and Tanzania were convened (with the facilitation of
FAO/EMPRES, OAU and EU) to co-ordinate surveillance and control efforts.
Concerted efforts by the two governments prevented the spread of rinderpest
to the Serengeti game reserve in Tanzania.
By October 1997, it was reported in the EMPRES Transboundary Animal
Disease Bulletin that "The potentially devastating outbreak of
rinderpest in East Africa early in 1997 has been contained by a concerted
emergency response at both national and international levels."
The outcome of this effort is that Tanzania has joined the OIE rinderpest
eradication pathway by declaring provisional freedom from rinderpest,
and southern Kenya will soon also be entering the pathway on a zonal
basis.
The effects of El Niño
By the end of 1997, the weather conditions had reversed, with abnormally
high rainfall being experienced throughout eastern Africa. The most
dramatic effects were experienced in the pastoral areas of southern
Somalia, eastern Kenya and northern Tanzania. The excessive moisture
in these areas completely changed the livestock disease picture from
one of drought-associated diseases to one of flood-related diseases.
In December 1997, unexplained human deaths were reported in the North
Eastern Province of Kenya and in southern Somalia. Surveys confirmed
the presence of a haemorrhagic syndrome (that is, fever with mucosal
or gastrointestinal bleeding), and some patients were found to have
acute infection of Rift Valley Fever (RVF) virus. RVF cases were confirmed
in people in the North Eastern, Central, Eastern, and Rift Valley Provinces
of Kenya, and in the Gedo, Hiran, and Lower Shabelle Provinces of Somalia.
Livestock losses of up to 70 percent in sheep and goats, and 20-30 percent
in cattle and camels, were also reported and surveys confirmed that
RVF was present in livestock in the Horn of Africa. However, a range
of other infections also contributed to the high mortality reported
in livestock - including non-specific pneumonia, pasteurellosis, contagious
caprine pleuropneumonia, contagious pustular dermatitis, bluetongue,
and complications of mange and non-specific foot rot. Sheep and goat
mortalities in Kenya alone probably exceeded 700 000 animals. In Tanzania,
it was reported that 50 percent of all young sheep and goats in the
affected areas died. Abortions were also recorded in cattle and camels,
mostly due to Rift Valley Fever.
There was a strong upswing in viral activity with simultaneous appearance
of the same diseases in different areas. RVF is a mosquito-borne disease,
and it is believed that the virus is maintained in inter-epidemic periods
in Aedes spp. mosquitoes. When there is an increase in surface
water and in increased number of vectors available, virus activity increases.
While it is possible that the number of livestock losses attributable
to RVF may only have formed a smaller proportion of the total number
of deaths, the presence of the disease triggered a trade ban. Somalia,
particularly, is a major livestock exporter to Saudi Arabia. In fact,
livestock exports account for most of Somalia's foreign exchange earnings.
Saudi Arabia banned all livestock imports from Somalia for fear of the
human health consequences of Rift Valley Fever.
A subsequent risk assessment by FAO/EMPRES showed that by March 1998,
the risk of RVF transmission to Saudi Arabia via livestock imports had
receded, probably to the levels existing before November 1997. The coast
was thus once again clear for exports to resume.
The Horn of Africa case is a classic example of a transboundary animal
disease directly having micro and macro economic effects including on
income and export earnings. Although the threats of rinderpest and Rift
Valley Fever have receded somewhat, the current situation in eastern
Africa is still far from satisfactory, and the following problems and
threats require attention.
Rinderpest continues to exist in the southern Sudan axis, and is believed
also to linger in parts of southern Somalia and possibly the contiguous
part of north-eastern Kenya, where it remains a threat to the south.
Peste de Petits Ruminants (PPR) is present in Sudan, Ethiopia and Somalia,
while the virus might have gained access to the northern parts of Uganda
and Kenya. A recent serological survey of northern Tanzania has shown
no evidence of PPR in this country so far. Contagious caprine pleuropneumonia
(CCPP) is present throughout the region and has recently been confirmed
to have extended into Tanzania. Contagious bovine pleuropneumonia (CBPP)
is constantly present in all the countries of the region and foot-and-mouth
disease (FMD) continues unchecked in many parts of the region.
Veterinary Services: support
required
At the root of some of these problems are poorly structured and poorly
resourced national veterinary services. Some critical areas requiring
attention are:
The pastoral areas of Kenya and Somalia require innovative approaches
to disease management and control. Somalia is particularly needy at
this time due to the unsettled conditions there. NGO initiatives, many
using volunteer community animal health workers, must be further supported.
Surveillance work to show the absence (or at least low risk) of important
transboundary infections would build confidence in these areas as a
source of livestock for marketing, and could be facilitated by regional
organisations.
In Tanzania, targeted rinderpest surveillance proved effective, but
countrywide livestock disease surveillance is much less effective. There
is an urgent need for more resources to the veterinary service, as well
as restructuring it so as to allow for rapid and direct reporting of
diseases from village to headquarters, as well as rapid and firm response
to outbreaks.
An enabling legislative environment must be created in the countries
of eastern Africa, and the necessary training given, to permit wider
use of community animal health workers. These, in turn, will need to
be supervised by qualified veterinary professionals.
The lessons learned from the recent rinderpest outbreak in eastern
Africa have underlined the importance of transborder surveillance/early
warning systems. These mechanisms must be promoted and their use extended
throughout the region under the leadership of appropriate regional organisations
such as OAU/IBAR.
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